PATHOGENS BACTERIA, PROTISTS, FUNGI, AND VIRUSES...

PROKARYOTAE; aka Bacteria…  Prokaryotic (no nucleus)  Genetic code; one single circular strand of DNA  Plasmids are DNA outside the chromosome  No membrane bound organelles  They do have ribosomes  Cell wall made of an amino-sugar called peptidoglycan  Pili are hair like appendages on outside of the bacteria; for attachment and reproduction

Structure…

Metabolism…  Most are heterotrophs  Feed off dead organic matter, symbiotic, and parasitic  Autotrophs; make their own food  Photosynthetic  Chemosynthetic

Respiration…  Obligate aerobes; need oxygen  Obligate anaerobes; oxygen kills them  Facultative anaerobes; with or without oxygen

REPRODUCTION  Asexual = binary fission (mitosis)  Sexual = conjugation; uses pili  Can reproduce as quickly as 20 minutes

BACTERIA CAN EXCHANGE GENETIC MATERIAL!!!  Plasmid: giving a chunk of DNA  Conjugation: swapping DNA via “pili”

Transfer of DNA…  Conjugation

Classification by Shape  Bacillis = Rod shaped  Coccus = Spherical  Spirillum = Spiral Shaped

SHAPES  Coccus  Spirillum  Bacillus

Classified by Organization… StrepStaphDiplo

Classified by Cell Wall Structure…  Gram Positive = Two layer membrane  Thick peptidoglycan cell wall  Plasma membrane under the cell wall  Purple  Gram Negative = Three layer membrane  Thin peptidogycan cell wall  Lipid membrane > petidoglycan cell wall > plasma membrane  Pink

Gram Positive vs. Gram Negative…

BACTERIA: THE GOOD, THE BAD, THE UGLY…  Bacteria can be pathogens…  Anthrax, tetanus, scarlet fever, strep throat…  Bacteria can be useful…  Nitrogen fixing; helps plants survive  Degrades wastes  Alternative energy sources  Produce plastics  Source of possible medicinal drugs

VIRUSES…

Characteristics…  Nucleic acid core; either DNA or RNA but never both  Capsid; protein coat surrounding the nucleic acid core  No ribosomes or organelles of any kind  No metabolism (doesn’t eat or breath)  Host cell reproduces the virus

Structure…

Infection cycle…  Lytic Cycle;  Attachment of virus on cell membrane  Injection of DNA or RNA into cytoplasm  Cell replicates virus RNA or DNA  Assembly of viral structure (capsid & DNA)  Release; cell bursts and viruses escape

Lytic Cycle

Other ways…  Lysogenic Cycle  Virus attaches  Viral DNA is injected into cell  Viral DNA is incorporated into host DNA  Cell divides and daughter cells contain the viral DNA; process continues  May go into lytic cycle ( scary )

Lysogenic cycle …

Retro-viruses  Retrovirus is a virus that contains only RNA.  Virus has its own reverse transcriptase, an enzyme that makes DNA from RNA.  New DNA molecule is incorporated into the hosts DNA.  Example: HIV

HIV

HIV Anatomy

HIV Genes

HIV Gene Expression

HIV Infection  Lytic cycle  Viral load usually large enough at 6 months after infection to test positive on ELISA or viral load tests  Contracted through blood transfusions, mothers milk, unprotected sexual contact, dirty needles…affects ALL ages, races, and genders!

Retrovirus…

HIV Therapies  Docking Proteins (CD-4)  Reverse transcriptase (block action)  Proteases block building of Virus Proteins  Integrases block integration of vDNA into host DNA  AZT prematurely ends viral DNA replication  Natural Immunities (CD-4 altered or super immunity)  Other? (vaccine?)

Viruses: The Good, The Bad, The Ugly…  Viruses can be pathogens…  HIV, Influenza, Herpes, Chicken Pox…  Linked to cancer: Mono, Herpes, Hepatitis  Germ warfare: small pox  Viruses can be useful…  Can be used to inject useful genetic codes  Example; bacteria produce insulin  Vaccines; polio, measles, hepatitis…

Protists…

PROTISTA (protozoans)  Eukaryote (has nucleus and membrane bound organelles)  Single-celled  Two major categories  Protists  Blue-green algae

Are they plants? Animals?? Fungi???  Some protists are plant like!  Blue-green algae are photosynthetic and are the basis for aquatic food chains  Protists are animal like!  Carnivorous (ex. paramecium)  Parasitic (ex. Plasmodium)  Protists are like Fungi too!  Slime molds digest decaying logs and leaves

Protists: The good, the bad, the ugly…  Good: Form the basis of food chains  Ex. Algae  Bad: Can cause crop damage  Ex. Slime molds  Ugly: Cause serious disease  Ex. Malaria and Giardia

Giardia life cycle…

Giardia…

Malaria life cycle…

Malaria…

Fungi…

Fungi are biologically “weird”…  May be one simple cell or millions.  Have cell walls but are made of sugar.  Organelles can move from one cell to another  They can’t move nor can they make their own food.  They digest food outside themselves then absorb it through their cell walls.  Can reproduce sexually or asexually

Structure of Multicellular Fungi…  Cell Wall: Made of chitin, a complex polysaccharide (sugar).  Hyphae: Threadlike filaments that develop from fugal spores.  Mycelium: Network of hyphae.  Anchor fungi, invade host cell, and reproductive structures  Septa: divide hyphae into individual cells  Porous, cytoplasm and organelles can move freely.

Hyphae Mycelium

The Septa…

Reproduction…  Fragmentation: hyphae are severed and grow into new mycelium  Ex. Shoveling in a garden  Budding: Single celled fungi splits in two  Ex. Yeast  Spores: hyphae grow away from fungi and produce a case containing spores  Ex. Mushrooms

Classified by eating habits  Saprophytes: Feed off dead plants and animals.  Ex. Bread mold, mushrooms, bracket fungi.  Symbionts: Live with other organisms, mutual benefit.  Ex. Lichen (fungi outside, algae inside)  Parasites: Live off live organisms  Ex. Cause of Athletes Foot, Ringworm, etc.

Fungi; The good, the bad, the ugly…  Good: decompose organic material, make antibiotics (penicillin).  Bad: destroys food, wood products, shower curtains, etc…  Ugly: Pathogenic (yeast infection, athletes foot, ring worm, etc.)

Ring worm…

Athletes foot…

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